[media] omap3isp: queue: Allocate kernel buffers with dma_alloc_coherent

And retrieve the related sg table using dma_get_sgtable().

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Sakari Ailus <sakari.ailus@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>